This invention is directed to an electronic timepiece calendar circuit, and in particular, to the automatic display of calendar information, such as date, month and year, by an electronic timepiece, without having to effect correction of the calendar circuitry at the end of each month or year.
Heretofore, mechanical wristwatches provided with calendar displays, have generally required that the wearer of the electronic timepiece, if same is a wristwatch, manually adjust the calendar wheel to a count of one after months such as February, April, June and November, that have less than 31 days. Although highly complex mechanical display calendar arrangements have been provided for eliminating this problem in mechanical watches, same have been found to be highly complicated and particularly large, thereby preventing their wholesale adoption in mechanical movement wristwatches having calendar mechanisms.
With the changeover from mechanical movement timepieces to fully electronic timepieces, and in particular, to digital display electronic timepieces of the LCD and/or LED type, electronic timepiece calendar displays that provide for automatic return of the date at the end of each month, without adjustment, have been suggested. Specifically, the date displayed by the calendar is automatically returned to a count of one after each 31 day month is automatically returned to a count of one after each 30 day month, and, after February, is returned to a count of one after 28 days. This arrangement however does not take into account the requirement that the date counter not be returned to a count of one during leap years until after the 29th day of the month. Accordingly, a timepiece that is not capable of detecting when a year is a leap year, requires mechanical adjustment of the timepiece at the end of February during each leap year, thereby requiring the complex mechanical manipulations that obtain in electronic wristwatches when correction of the time displayed by the counters needs to be corrected. Therefore, a leap year counter and judging circuit for permitting the year to be displayed and for effecting automatic adjustment of the date displayed over a period of at least 20 years, is provided.